Components like resistors, capacitors and transistors will never be exact when implemented on silicon chips, and there will be a variation around the desired component value. The matching between components of the same type may be quite good. This may be achieved when the components are of similar dimensions, oriented in the same direction and placed close to each other. Often, matching between components of the same type is more important than the exact values of the components. Sometimes, more exact component values are needed, which may require trimming. Also secondary properties, like voltage levels, currents, oscillator frequencies and filter bandwidths may sometimes require trimming. The components, voltages, currents etc. that need to be accurate may be designed to be programmable, which may be controlled by trim bits, i.e. a trim value represented by a number of bits which is provided to the programmable component. On-chip components may be made up of several smaller parts that are connected in series or parallel to provide the properties of the component. The trimming may be digitally controlled and the parts of the components may be switched in or out, depending on the value of the trim data set. The trimming may be done by software after boot and the trim settings may for example be stored in on-chip memory cells that may lose their information when supply power is lost. However, analog baseband or power management circuits in for example communication apparatuses may be intended to operate even before boot when no other circuits are operational and consequently, the trimming cannot in such situations be done by software. Instead, the trimming is done once during manufacturing of the circuits, and the trim settings may be stored in on-chip One Time Programmable (OTP) memory cells. These may typically be metal fuses, Electrically Erasable Programmable Read Only Memory (EEPROM) cells or something similar. Such memories often require a large silicon area and the memory capacity may therefore for practical reasons be limited. Consequently, trim bits may be considered as “expensive” and are normally only be used when really crucial. If all trimmed components, currents etc use their own set of trim bits, like illustrated in FIG. 1, a large amount of the “expensive” trim bits would be required. Alternatively, an approach may be to trim one component and then use the same trim settings also for similar components like illustrated in FIG. 2. This requires that the matching is good between the components and that the trimming ranges are proportional. If the components are more distant from each other, of different orientation or dimensions, then the matching will be worse but there will probably still be some correlation. This method will probably give some improvement even when the components are not well matched. However, the result may not be predictable enough for some designs. The design rules for matching between components normally require that the components are adjacent to each other and it is very hard to guarantee any specific matching if this requirement is not met.
There is a desire to improve trimming, and/or limit consumed circuit area for the trimming.